Detect castling, en-passant and captures

chess/__init__.py

@@ -2182,10 +2182,6 @@ def san(self, move):
 
         if piece == PAWN:
             san = ""
-
-            # Detect en-passant.
-            if not BB_SQUARES[move.to_square] & self.occupied:
-                en_passant = abs(move.from_square - move.to_square) in (7, 9)
         else:
             # Get ambigous move candidates.
             if piece == KNIGHT:
@@ -2229,7 +2225,7 @@ def san(self, move):
                     san += str(rank_index(move.from_square) + 1)
 
         # Captures.
-        if BB_SQUARES[move.to_square] & self.occupied or en_passant:
+        if self.is_capture(move):
             if piece == PAWN:
                 san += FILE_NAMES[file_index(move.from_square)]
             san += "x"
@@ -2249,6 +2245,29 @@ def san(self, move):
 
         return san
 
+    def is_en_passant(self, move):
+        """Checks if the given pseudo-legal move is an en-passant capture."""
+        diff = abs(move.to_square - move.from_square)
+
+        if not diff in (7, 9):
+            return False
+
+        if not self.pawns & BB_SQUARES[move.from_square]:
+            return False
+
+        if self.occupied & BB_SQUARES[move.to_square]:
+            return False
+
+        return True
+
+    def is_capture(self, move):
+        """Checks if the given pseudo-legal move is a capture."""
+        return BB_SQUARES[move.to_square] & self.occupied_co[self.turn ^ 1] or self.is_en_passant(move)
+
+    def is_castling(self, move):
+        """Checks if the given pseudo-legal move is a castling move."""
+        return bool(BB_SQUARES[move.to_square] & self.occupied_co[self.turn])
+
     def status(self, allow_chess960=True):
         """
         Gets a bitmask of possible problems with the position.

chess/syzygy.py

@@ -1376,8 +1376,7 @@ def probe_wdl(self, board):
         # Look at least at all legal en-passant captures.
         for move in board.generate_legal_moves(castling=False, pawns=True, knights=False, bishops=False, rooks=False, queens=False, king=False):
             # Filter out non-en-passant moves.
-            diff = abs(move.to_square - move.from_square)
-            if not ((diff == 7 or diff == 9) and not board.occupied & chess.BB_SQUARES[move.to_square]):
+            if not board.is_en_passant(move):
                 continue
 
             # Do the move.
@@ -1398,21 +1397,10 @@ def probe_wdl(self, board):
             if v1 >= v:
                 v = v1
             elif v == 0:
-                # Check whether there is at least one legal non-ep move.
-                found_move = False
-                for move in board.generate_legal_moves():
-                    if board.piece_type_at(move.from_square) != chess.PAWN:
-                        found_move = True
-                        break
-
-                    diff = abs(move.to_square - move.from_square)
-                    if not ((diff == 7 or diff == 9) and not board.occupied & chess.BB_SQUARES[move.to_square]):
-                        found_move = True
-                        break
-
-                    # If not, then we are forced to play the losing ep capture.
-                    if not found_move:
-                        v = v1
+                # If there is not at least one legal non-en-passant move we are
+                # forced to play the losing en-passant cature.
+                if all(board.is_en_passant(move) for move in board.generate_legal_moves()):
+                    v = v1
 
         return v
 
@@ -1436,10 +1424,9 @@ def probe_dtz_no_ep(self, board):
             return 1 if wdl == 2 else 101
 
         if wdl > 0:
-            # Generate all legal non capturing pawn moves.
+            # Generate all legal non-capturing pawn moves.
             for move in board.generate_legal_moves(castling=False, pawns=True, knights=False, bishops=False, rooks=False, queens=False, king=False):
-                diff = abs(move.to_square - move.from_square)
-                if diff == 7 or diff == 9:
+                if board.is_capture(move):
                     continue
 
                 board.push(move)
@@ -1552,8 +1539,7 @@ def probe_dtz(self, board):
 
         for move in board.generate_legal_moves(castling=False, pawns=True, knights=False, bishops=False, rooks=False, queens=False, king=False):
             # Filter out non-en-passant moves.
-            diff = abs(move.to_square - move.from_square)
-            if not ((diff == 7 or diff == 9) and not board.occupied & chess.BB_SQUARES[move.to_square]):
+            if not board.is_en_passant(move):
                 continue
 
             board.push(move)
@@ -1586,18 +1572,7 @@ def probe_dtz(self, board):
             elif v1 >= 0:
                 v = v1
             else:
-                found_move = False
-                for move in board.generate_legal_moves():
-                    if board.piece_type_at(move.from_square) != chess.PAWN:
-                        found_move = True
-                        break
-
-                    diff = abs(move.to_square - move.from_square)
-                    if not ((diff == 7 or diff == 9) and not board.occupied & chess.BB_SQUARES[move.to_square]):
-                        found_move = True
-                        break
-
-                if not found_move:
+                if all(board.is_en_passant(move) for move in board.generate_legal_moves()):
                     v = v1
 
         return v

test.py

@@ -877,6 +877,29 @@ def test_string_conversion(self):
         self.assertFalse(u"♜" in html)
         self.assertFalse(u"♖" in html)
 
+    def test_move_info(self):
+        board = chess.Board("r1bqkb1r/p3np2/2n1p2p/1p4pP/2pP4/4PQ1N/1P2BPP1/RNB1K2R w KQkq g6 0 11")
+
+        self.assertTrue(board.is_capture(board.parse_san("Qxf7+")))
+        self.assertFalse(board.is_en_passant(board.parse_san("Qxf7+")))
+        self.assertFalse(board.is_castling(board.parse_san("Qxf7+")))
+
+        self.assertTrue(board.is_capture(board.parse_san("hxg6")))
+        self.assertTrue(board.is_en_passant(board.parse_san("hxg6")))
+        self.assertFalse(board.is_castling(board.parse_san("hxg6")))
+
+        self.assertFalse(board.is_capture(board.parse_san("b3")))
+        self.assertFalse(board.is_en_passant(board.parse_san("b3")))
+        self.assertFalse(board.is_castling(board.parse_san("b3")))
+
+        self.assertFalse(board.is_capture(board.parse_san("Ra6")))
+        self.assertFalse(board.is_en_passant(board.parse_san("Ra6")))
+        self.assertFalse(board.is_castling(board.parse_san("Ra6")))
+
+        self.assertFalse(board.is_capture(board.parse_san("O-O")))
+        self.assertFalse(board.is_en_passant(board.parse_san("O-O")))
+        self.assertTrue(board.is_castling(board.parse_san("O-O")))
+
 
 class LegalMoveGeneratorTestCase(unittest.TestCase):